A metal plate on a multi-die LED emitter substrate or a metal plate on a metal-core printed circuit board (MCPCB) that attaches to the emitter substrate (or both plates) can be fabricated with a number of generally radial grooves, at least some of which extend to the peripheral edge of the plate. These grooves can provide channels that allow air to escape during solder-bonding processes, reducing the size and/or total area of solder voids and thereby improving thermal transfer between the emitter and the MCPCB.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A printed circuit board for bonding to an emitter substrate supporting light emitting devices, the printed circuit board comprising: a first insulating layer; and a metal plate on a top surface of the first insulating layer, the metal plate having a plurality of grooves therein, wherein at least some of the grooves have an inner end at a first distance from a center of the metal plate and an outer end at a peripheral edge of the metal plate, wherein the at least some of the grooves have a uniform depth from the inner end to the outer end, the uniform depth being at least equal to a thickness of the metal plate such that a portion of the first insulating layer is exposed at a bottom of the groove.
2. The printed circuit board of claim 1 further comprising: a second insulating layer parallel to and below the first insulating layer; and at least one patterned layer of conductive material disposed between a bottom surface of the first insulating layer and a top surface of the second insulating layer.
3. The printed circuit board of claim 2 further comprising: a plurality of metal contact pads disposed on the top surface of the first insulating layer, wherein at least one of the plurality of metal contact pads is electrically connected to the conductive material of the patterned layer.
4. The printed circuit board of claim 1 wherein the metal plate is circular.
5. The printed circuit board of claim 1 wherein the first distance is zero.
6. The printed circuit board of claim 1 wherein the first distance is greater than zero.
7. The printed circuit board of claim 1 wherein the plurality of grooves further includes at least one groove having an inner end at the center of the metal plate and an outer end at a second distance from the center, wherein the second distance is less than a distance from the center of the metal plate to the peripheral edge of the metal plate.
8. The printed circuit board of claim 7 wherein the second distance is equal to the first distance.
9. The printed circuit board of claim 7 wherein the second distance is less than the first distance.
10. The printed circuit board of claim 1 wherein respective outer ends of all of the plurality of radial grooves are at the peripheral edge of the metal plate.
11. The printed circuit board of claim 1 wherein the number of grooves and width of each groove is selected such that an area occupied by the grooves is less than 15% of a total area of the metal plate.
12. The printed circuit board of claim 1 wherein the at least some of the plurality of grooves each have a width that is uniform along a length of the groove.
13. An emitter for a light emitting device, the emitter comprising: an emitter substrate having a top surface adapted to support a plurality of light emitting diodes and a bottom surface; and a metal plate disposed on the bottom surface of the emitter substrate, the metal plate having a plurality of grooves therein, wherein at least some of the grooves have an inner end at a first distance from a center of the metal plate and an outer end at a peripheral edge of the metal plate, wherein the at least some of the grooves have a uniform depth from the inner end to the outer end, the uniform depth being at least equal to a thickness of the metal plate such that a portion of the first insulating layer is exposed at a bottom of the groove.
14. The emitter of claim 13 wherein the metal plate is circular.
15. The emitter of claim 13 wherein the first distance is zero.
16. The emitter of claim 13 wherein the first distance is greater than zero.
17. The emitter of claim 13 wherein the plurality of grooves further includes at least one groove having an inner end at the center of the metal plate and an outer end at a second distance from the center, wherein the second distance is less than a distance from the center of the metal plate to the peripheral edge of the metal plate.
18. The emitter of claim 13 wherein the number of grooves and width of each groove is selected such that an area occupied by the grooves is less than 15% of a total area of the metal plate.
19. The emitter of claim 13 wherein the at least some of the plurality of grooves each have a width that is uniform along a length of the groove.
20. A light emitting device comprising: a printed circuit board having a first insulating layer and a first metal plate on a top surface of the first insulating layer; an emitter substrate having a top surface holding a plurality of light emitting diodes and a bottom surface having a second metal plate thereon; and a solder layer disposed between and bonded to the first metal plate and the second metal plate, wherein the first metal plate has a plurality of grooves therein, wherein at least some of the grooves have an inner end at a first distance from a center of the first metal plate and an outer end at a peripheral edge of the first metal plate, wherein the at least some of the grooves have a uniform depth from the inner end to the outer end, the uniform depth being at least equal to a thickness of the metal plate such that a portion of the first insulating layer is exposed at a bottom of the groove, wherein a solder material of the solder layer fills in the plurality of grooves.
21. The light emitting device of claim 20 wherein the first and second metal plates are circular.
22. The light emitting device of claim 20 wherein the first distance is zero.
23. The light emitting device of claim 20 wherein the plurality of grooves further includes at least one groove having an inner end at the center of the metal plate and an outer end at a second distance from the center, wherein the second distance is less than a distance from the center of the metal plate to the peripheral edge of the metal plate.
24. The light emitting device of claim 20 wherein respective outer ends of all of the plurality of radial grooves are at the peripheral edge of the metal plate.
25. The light emitting device of claim 20 wherein the number of grooves and width of each groove is selected such that an area occupied by the grooves is less than 15% of a total area of the metal plate.
26. The light emitting device of claim 20 wherein the at least some of the plurality of grooves each have a width that is uniform along a length of the groove.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
October 11, 2011
November 19, 2013
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